232 EXPERIMENT STATION RECORD. 



potash; ammonium sulphate, superphosphate; ammonium sulphate, superphos- 

 phate, sulphate of potash; ammonium sulphate] were selected, 10 clumps from 

 a plat, and analyzed separately to determine any influence of fertilizer on the 

 sulphur, chlorin. phosphoric acid composition on the straw and paddy of rice." 

 No difference in the sulphur or chlorin composition of the plant was noted, 

 although the ammonium sulphate plat showed a slight depression of the phos- 

 phoric acid absorbed by the plants. 



The ix)ssibility of sulphur fertilization being required by a crop that absorbs 

 about half as much sulphur as it does phosphoric acid for organic material 

 is pointed out. A partial analysis of the soil from the rice trial grounds of 

 the station is shown. " The results indicate that the sulphur in the soil is 

 present largely in organic form, since the acid soluble and water soluble sulphur 

 are relatively so small. No trace of sulphid was found on boiling the soil with 

 hydrochloric acid. Doubtless the presence of large amounts of iron in the soil 

 results in the formation of insoluble basic compounds of sulphur, and tliis may 

 explain the noneftect of sulphur fertilizer on the composition of rice plants 

 grown in the soil, for ... in silica sand cultures the composition is much affected. 

 . . . The soil contains an abundance of phosphoric acid but no large amount 

 of chlorin." The water entering the rice field showed a SO3 content of about 

 9 parts per million, and a chlorin content of about TO parts per million. 



Samples of rice grown in pot cultures in the nitrogen work previously 

 reported (E. S. R., 26, p. 41) were also compared with plants grown in the 

 trial ground. The plants in the pots had received in addition to a basic fer- 

 tilizer lacking nitrates, calcium sulphate and several forms of nitrogen. No 

 consistent influence could be noted in the sulphur of the plants grown in the pots 

 containing trial ground soil, but " in those plants gi'own in the silica sand pots, 

 the total sulphur content is higher in every case and constantly higher when 

 the soluble ammonium sulphate was the fertilizer added." The increase in 

 total sulphur is deemed undoubtedly due to the absorption of mineral sulphur 

 by the plant. The phosphoric acid content was fairly constant through the 

 series of plants. 



For the purpose of verifying results obtained with the pot plants, some fur- 

 ther experiments were made with silica sand pots. " The chlorin absorbed was 

 about twice as high as that absorbed by the rice plant grown in normal soil 

 conditions. These results with silica sand cultures show the sulphur fertilizer 

 is not rendered insoluble to the plant as is the case in soil cultures. They show 

 the probability of the absorption of ammonium sulphate as such by the rice 

 plant as so much mineral sulphate is found in the foliage, and free ammonia 

 was determined in the water solution of 2 rice plant samples." 



Some determinations of phosphoric acid in solutions obtained from sulphur 

 determinations by fusion with sodium peroxid v.-ere made, the molybdic precipi- 

 tate being dissolved and reprecipitated for the purpose of removing the silica. 

 The results compare favorably witli those obtained by ignition with the mag- 

 nesium nitrate (official) method. By comparing the results obtained by boiling 

 samples of straw and grain with hydrochloric acid and nitric acid with those 

 obtained by boiling with sulphuric acid and potassium nitrate, it is seen that the 

 2 methods, when applied to the straw, are not greatly different, while those 

 obtained by boiling the grain with aqua regia until a colorless solution results, 

 are about one-third as high as those obtained by the sulphuric acid and potas- 

 sium nitrate method. "Although the solution ef the grain obtained by boiling 

 with hydrochloric acid and nitric acid becomes practically colorless, organic 

 matter is still present, as shown by the charred mass that results if it is boiled 

 to diyness. The starch may be oxidized to some organic acid that resists oxida- 

 tion and interferes with the precipitation of the phosphomolybdic precipitate." 



